common sea hare vs Compressed Flapwort

Aplysia punctata compared with Nardia compressa

Taxonomic Classification

Rank	common sea hare	Compressed Flapwort
Kingdom	Animalia (Animals)	Plantae (Plants)
Phylum	Mollusca (Mollusks)	Marchantiophyta (liverwort)
Class	Gastropoda (Gastropoda)	Jungermanniopsida (Jungermanniopsida)
Order	Aplysiida (Aplysiida)	Jungermanniales (Jungermanniales)
Family	Aplysiidae	Gymnomitriaceae
Genus	Aplysia	Nardia
Species	Aplysia punctata	Nardia compressa

Conservation Status

common sea hare

LC — Least Concern

Compressed Flapwort

LC — Least Concern

Physical Characteristics

Attribute	common sea hare	Compressed Flapwort
Diet	—	—
Average Lifespan	—	—
Average Length	—	—
Average Weight	—	—

Habitat & Geographic Range

common sea hare

Habitat

Typically found in terrestrial and aquatic habitats including forests and freshwater.

Range

Distributed across Denmark, Norway, Portugal, and Sweden.

Compressed Flapwort

Habitat

Native to Europe, inhabiting ecosystems characteristic of the region.

Range

Distributed across Belgium, Norway, and Sweden.

common sea hare

<em>Aplysia punctata</em>, the common sea hare, is a large opisthobranch sea slug in the family Aplysiidae, order Aplysiida, found in the northeastern Atlantic Ocean and Mediterranean Sea, with confirmed records from Denmark, Norway, Portugal, and Sweden. This species typically inhabits shallow subtidal and intertidal zones with abundant macroalgae, feeding primarily on red and green algae — a diet that influences the color of the defensive purple ink it secretes when threatened. <em>Aplysia punctata</em> is a simultaneous hermaphrodite, capable of acting as both male and female during mating, and often forms mating chains involving multiple individuals. It can reach considerable size among European opisthobranch species, though body dimensions vary considerably with age and feeding conditions. The species is classified as Least Concern by the IUCN, reflecting stable populations across its coastal range. Biological traits for this species remain poorly documented in the scientific literature, including precise average data on lifespan, body length, weight, and detailed seasonal dietary patterns, though its general herbivorous feeding on macroalgae is well established.

Compressed Flapwort

<em>Nardia compressa</em>, commonly called the Compressed Flapwort, is a leafy liverwort in the family Jungermanniaceae, a lineage of non-vascular land plants (division Marchantiophyta) that diverged from other embryophytes over 400 million years ago. This small, mat-forming bryophyte typically colonizes moist, acidic substrates along stream banks, seepages, and wet rock faces in cool-temperate habitats throughout Europe. Its flattened, overlapping leaves give the plant a compressed appearance, which inspired both its common and scientific names. Like all liverworts, <em>Nardia compressa</em> lacks true vascular tissue and absorbs water and nutrients directly through its leaf surfaces, deriving energy through photosynthesis rather than heterotrophic feeding. The species has been recorded in Belgium, Norway, and Sweden, suggesting an affinity for the moist, boreal and Atlantic climatic zones of northwestern and northern Europe. It is currently assessed as Least Concern by the IUCN, indicating no immediate extinction risk across its known range. Biological traits including individual lifespan, reproductive rates, and specific growth measurements remain poorly documented relative to vascular plant species, though liverworts are generally slow-growing perennial organisms tightly dependent on stable moisture regimes.

Shared Countries

Both species can be found in 2 countries:

🇳🇴 Norway 🇸🇪 Sweden